Materials

Used materials:

  • Arduino UNO
  • Arduino protoshield
  • PCB board
  • Resistors
    • 11 x 100 Ω
    • 3 x 10 kΩ
    • 1 x 470 kΩ
    • 1 x 1 kΩ
  • Capacitors
    • 1 x 10 μF
    • 1 x 100 nF
  • Unidirectional electret microphone
  • LT1490 operational amplifier
  • LEDs
    • 6 x yellow
    • 2 x Red
    • 1 x Green
  • 8-pin socket
  • Wires (many wires)
  • USB-cable (for powering the Arduino)

Alternatives

Some components can be replaced by similar ones.

  • The electret mic does not need to be unidirectional. We also tried omnidirectional ones, but they were noisier.
  • Instead of the PCB and Protoshield, you can build the circuits in a breadboard. It is just a matter of presentation.
  • The LT1490 can be replaced by a similar op amp. They should be single supply and rail-to-rail op amps.
  • Resistors used to make voltage dividers can be of any other values. Just remember that the pair of resistors must be of the same value.
  • Capacitors do not need to be of the exact value, capacitors of similar values should work.
  • Naturally, LEDs of different colors can be used.